Photochromic naphthopyrans

ABSTRACT

The present invention relates to photochromic 2H-naphtho[1,2-b]pyrans as well as their use in synthetic resins of all types, especially for ophthalmic purposes. In particular, the present invention relates to photochromic naphthopyran compounds, for which a further ring system is bonded to the f side of the naphthopyran. The inventive photochromic dyes generally have the general formula (I)  
                 
 
     wherein n, R 1 , R 2 , R 3 , X, B and B′ are defined as in claim 1. The inventive compounds are distinguished by good darkening and decolorizing properties and a very good service life.

[0001] The present invention relates to photochromic2H-naphtho[1,2-b]pyrans as well as to their use in synthetic resins ofall types, particularly for ophthalmic purposes. In particular, thepresent invention relates to photochromic naphthopyran compounds, forwhich a further ring system is bonded to the f side of the naphthopyran.

[0002] Different classes of dyes are known which, when irradiated withlight of particular wavelengths, particularly sunlight, change theircolor reversibly. This is due to the fact that, because energy issupplied in the form of light, these dye molecules change over into astimulated colored state, which they leave once again when the supply ofenergy is interrupted in order to return to their colorless or at leasthardly colored normal state. These photochromic dyes include, forexample, the naphthopyrans, which have already been described withdifferent substituents in the state of the art.

[0003] Pyrans, especially naphthopyrans and larger ring systems derivedfrom these, are photochromic compounds, which until now have been theobject of intensive investigations. Although the first patent was filedalready in 1966 (U.S. Pat. No. 3,567,605), compounds, which are suitablefor use in eyeglass lenses, were developed only in the 1990s.

[0004] A suitable class of pyran compounds is, for example, the2,2-diaryl-2H-naphtho[1,2-b]pyrans. 2H-Naphtho[1,2-b]pyrans generallyare orange to red photochromic compounds, which are decolorized veryslowly after they have become darker, such as the Comparison Examples 4and 5 and the Comparison Example A in U.S. Pat. No. 5,066,818.

[0005] Attempts were made to achieve improvements here by substitutingthe carbon atoms in the 5 and 6 positions of the naphthalene part in thenaphthopyran. Compounds of this type are described, for instance, inU.S. Pat. Nos. 5,458,814, 5,573,712, 5,650,098, 5,656,206, 5,658,500 and5,658,501 and in WO 98/04937. Since there was a need for furtherimprovement, 2H-naphtho[1,2-b]pyran systems were described for the firsttime in U.S. Pat. No. 5,651,923. At the f side of the naphthopyran, thatis, at the naphthalene part, these compounds have condensed benzothieno,benzofurano or indolo system, the benzothieno, benzofurano and indolosystems being bound to the naphthalene via the heterocyclic portion. Itis disadvantage of the three naphthofuro[2′,3′:3,4]- andnaphthofuro[3′,2′3,4]-naphtho[1,2-b]pyrans of Examples 4, 5 and 6 inU.S. Pat. No. 5,651,923, that these decolorize very slowly and/or have avery slight photochromic efficiency (AOD). Indolonaphthopyrans alsodecolorize similarly slowly. In the WO 99/20619,pentahydrophenanthro[9,10-b]pyrans andtetrahydrocyclopenta[c]naphtho[1,2-b]pyrans are described, which alsohave the disadvantage that their decolorizing rate is slow and thereforeunsatisfactory for practical use in sunglasses.

[0006] In addition, an expensive and long synthesis route is requiredfor the systems described. Furthermore, due to the possibility ofconjugating with a further aromatic ring (system), a bathochromic shiftrelative to the basic absorption of the naphthopyran system may beobserved, which frequently is undesirable. This applies likewise for thecompounds in U.S. Pat. No. 5,645,767, which relate exclusively toindeno[2,1-f]naphtho[1,2-b]pyrans. Further continuations may be found inU.S. Pat. Nos. 5,698,141 and 5,723,072, which additionally havecondensed unsubstituted, monosubstituted or disubstituted heterocyclicsystems.

[0007] The known compounds are however associated with disadvantages,which affect the wearing comfort of the eyeglasses when thesephotochromic dyes are used in sunglass lenses. The known dyes have aninadequate long-wave absorption in the excited as well as in thenot-excited state. This leads to problems even when these compounds arecombined with other photochromic dyes. The temperature sensitivity withrespect to the darkening is too high. At the same time, thedecolorization frequently is too slow. In addition, the dyes describedhave an inadequate service life and, with that, in insufficientdurability in sunglass lenses. The latter becomes noticeable in arapidly abating efficiency and/or in severe yellowing. Moreover, thesynthesis of the compounds, described in the state of the art, usuallyis expensive and lengthy and generally does not permit further opticallyinteresting properties, such as a nonlinearity, to be incorporated intothe respective structures.

[0008] Accordingly, it is an object of the present invention to makeavailable new photochromic compounds, which have improved properties incomparison to the structures described in the state of the art. Thephotochromic compounds are to be distinguished particularly owing to thefact that they have faster kinetics in the light-stimulated state, thando comparable compounds from the state of the art, and exhibit a betterbehavior in the service life test.

[0009] This objective is accomplished by the objects, characterized inthe claims. In particular, photochromic 2H-naphtho-[1,2-b]pyrans of thegeneral formula (I) are made available

[0010] wherein

[0011] X represents a ring element with 2 to 4 saturated and/orunsaturated carbon atoms, of which not more than one can be replaced bya hetero atom, selected from the group comprising O, S and NR₄, R₄ beinga linear or branched C₁ to C₆ alkyl group, a substituted orunsubstituted C₅ to C₇ cycloalkyl group, a substituted or unsubstitutedphenyl group or a substituted or unsubstituted benzyl group;

[0012] R₁ is a substituent, selected from group A, comprising a C₁ to C₆alkyl group, a C₁ to C₆ alkoxy group, a C₃ to C₇ cycloalkyl group, whichmay have one or more hetero atoms, a phenyl group, a hydroxy group,bromine, chlorine and fluorine, n being 0, 1 or 2;

[0013] R₂, R₃ independently of one another are groups, selected fromgroup G, comprising hydrogen, hydroxy, a C₁ to C₆ alkyl group, a C₁ toC₆ alkoxy group, a C₃ to C₇ cycloalkyl group, an unsubstituted,monosubstituted and disubstituted phenyl group and an unsubstituted,monosubstituted and disubstituted naphthyl group and the aromaticgroups, selected from group C, comprising benzene, naphthalene,phenanthrene, pyridine, quinoline, furan, thiophene, pyrrol, benzofuran,benzothiophene, indol and carbazol, the substituent or substituents ofthe aforementioned aromatic groups being selected from group A; or R₂and R₃ together, with inclusion of the spiro carbon atom, form a5-membered to 1 -membered ring, to which one or several aromatic orheteroaromatic ring systems may be annellated, the aromatic orheteroaromatic ring system or systems being one of the aforementionedgroup C; or R₂ and R₃ together represent an oxygen atom with formationof a carbonyl group; with the proviso that, when X is —(CH₂)₂— or—(CH₂)₃— and R₂ and R₃ are not at the same time hydrogen;

[0014] B, B′ are selected independently of one another from thefollowing groups a), b) or c), wherein

[0015] a) are mono-, di- and trisubstituted aryl groups, the aryl groupbeing phenyl or naphthyl;

[0016] b) are unsubstituted, mono- and disubstituted heteroaryl groups,the heteroaryl group being pyridyl, furanyl, benzofuran-2-yl,benzofuran-3-yl, thienyl, benzothien-2-yl or benzothien-3-yl; thesubstituents of the aryl groups or the heteroaryl groups in a) and b)being selected from a group comprising hydroxy, amino, mono-(C₁ toC₆)-alkylamino, di-(C₁ to C₆)-alkylamino, mono- and diphenylamino,unsubstituted, monosubstituted or disubstituted at the aromatic ring,piperidinyl, morpholinyl, carbazolyl, unsubstituted, monosubstituted anddisubstituted pyrryl, C₁ to C₆ alkyl, C₁ to C₆ alkoxy, bromine, chlorineand fluorine, wherein the aforementioned aromatic and heteroaromaticring systems can be substituted with C₁ to C₆ alkyl, C₁ to C₆ alkoxy,bromine, chlorine and fluorine;

[0017] c) are structure units with the following formulas (V) and (W)

[0018] wherein

[0019] Y and Z, independently of one another are O, S, CH, CH₂ or NR₈,the R₈ group is selected from the group D comprising C₁ to C₆ alkyl, C₁to C₆ acyl and hydrogen, and R₅ in each case is a substituent from groupA, n being defined as above; and R₆ and R₇, independently of oneanother, are hydrogen and/or a C₁ to C₆ alkyl group, with the provisothat, when Y in formula (V) is NR₈, Z is a carbon atom;

[0020] or

[0021] d) B and B′ form with one another an unsubstituted,monosubstituted or disubstituted fluorene-9-ylidene group or a saturatedhydrocarbon group, which is C₃ to C₁₂, spiro-monocyclic, C₇ to C₁₂spiro-bicyclic and/or C₇-C₁₂ spiro-tricyclic, the fluoreno substituentsbeing selected from Group A.

[0022] Pursuant to the invention, compounds, the absorption wavelengthsof which are hardly shifted from those of the framework, but which, atthe same time, show in a surprising manner a significantly improveddecolorization in comparison to compounds of the state of the art, areprepared by a simple ring formation at the f side of the naphthopyranframework. Compared to the pentahydrophenanthro[9,10-b]pyrans andtetrahydrocyclopenta[c]-naphtho[1,2-b]pyrans, which are described in theWO 99/20619 and differ from the inventive napthopyrans owing to the factthat an unsubstituted cyclopentane ring or an unsubstituted cyclohexanering, in which X is —(CH₂)₂— or —(CH₂)₃— and R₂ and R₃ each arehydrogen, is linked at the f side of the naphthopyran framework, theinventive compounds exhibit a distinctly more rapid decolorization andsignificant improvements in the service life. Furthermore, yellowing nolonger occurs in the case of the inventive compounds.

[0023] In a preferred embodiment, the carbon atoms in the X ring elementare saturated, as a result of which corresponding cycloaliphatic ringsystems, substituted with the R₂ and R₃ groups, are formed at the f sideof the naphthopyran.

[0024] The carbon atoms in the X ring element may be unsubstituted, aswell as monosubstituted or disubstituted. In the latter case, thesubstituents or substituents may be selected from group A consisting ofC₁ to C₆ alkyl, C₁ to C₆ alkoxy, phenyl, bromine, chlorine and fluorine.

[0025] Pursuant to the present invention, photochromic2H-naphtho[1,2-b]pyrans of formula (I) are also prepared, whichstructurally have spiro systems annellated at the f side of thenaphthopyran system, the spiro system being formed by the ring system,formed by the ring element X at the f side of the naphthopyran, and theR₂ and R₃ group bound to the central spiro carbon atom. The R₂ and R₃groups together with inclusion of the spiro carbon atoms, form a 5- to11-membered ring and preferably a 5- to 7-membered ring, to which onceagain aromatic or heteroaromatic ring systems can be annellated. Inother words, adjacent carbon atoms in the part of the spiro system,formed by R₂ and R₃, can belong to further ring systems, namely a ringsystem from the C group, consisting of benzene, naphthalene,phenanthrene, pyridine, quinoline, furan, thiophene, pyrrol, benzofuran,benzothiophene, indol and carbazol. Of course, these ring systems ofgroup C can be unsubstituted as well as monosubstituted ordisubstituted, the substituents being selected from the group A definedabove.

[0026] Photochromic 2H-naphtho[1,2-b]pyrans, produced pursuant to theinvention, have the following general formula (II),

[0027] wherein n, R₁, R₂, R₃ and X are defined as above with the provisothat the R₁ groups and n in each case can be the same or different.

[0028] In a further embodiment, photochromic 2H-naphtho[1,2-b]pyrans areprepared, which have the following formula (III),

[0029] wherein n, R₁, X, B and B′ are defined as above.

[0030] Especially preferred inventive compounds are:

[0031] 1)spiro-9′-xanthene-5-[2-(4-methoxyphenyl)-2-phenyl-5,6,7,8-tetrahydro-6,6,7,7-tetramethyl-phenanthro[9,10-b]pyran]

[0032] 2)spiro-9′-fluorene-5-{2-[4-(N-morpholinyl)phenyl]-2-phenyl-5,6,7,8-tetrahydrophenanthro[9,10-b]pyran}

[0033] 3)5-hydroxy-2,2,5-triphenyl-5,6,7,8-tetrahydro-phenanthro[9,10-b]pyran

[0034] 4)spiro-9′-{(9,10-dihydroanthracene)-5-[2,2-bis(4-methoxyphenyl)]-cyclopenta[f]naphtho[1,2-b]pyran}

[0035] 5)2-[4-(N-morpholinyl)phenyl]-2-phenyl-5-oxo-cyclopenta[f]naphthopyran

[0036] 6)2-[4-(N-morpholinyl)phenyl]-2-phenyl-5,6,7,8-tetrahydro-5-oxo-phenanthro[9,10-b]pyran]

[0037] 7)spiro-9′-fluorene-5-[2-(4-methoxyphenyl)-2-phenyl-cyclopenta-[f]naphtho[1,2-b]pyran]

[0038] 8)spiro-9′-xanthene-5-{-2-[4-(N-morpholinyl)phenyl]-2-phenyl-5,6,7,8-tetrahydro-6,6,7,7,-tetramethyl-phenanthro[9,10-b]pyran}

[0039] 9)spiro-9′-fluorene-5-[2-(4-methoxyphenyl)-2-phenyl-cyclohepta[f]naphtho[1,2-b]pyran]and

[0040] 10)spiro-9′-fluorene-5-[2-(4-methoxyphenyl)-2-phenyl-oxepano[3,2-f]naphtho[1,2-b]pyran].

[0041] The inventive, photochromic 2H-naphtho[1,2-b]pyrans with thegeneral formula (I) can be synthesized employing principles, which arebasically known in the field. In this connection, reference is madeparticularly to the synthesis methods described in WO 99/15518 and inthe German patent application 199 02 771.4. For example, the inventivephotochromic 2H-naphtho[1,2-b]pyrans can be synthesized according to thefollowing general outline of the reactions, without being limited tothese, n, X, R₂, R₂, R₃, B and B′ being defined as above.

[0042] The keto group can be derivatized in the second step of thegeneral reaction outline by generally known methods, such as thereaction with appropriate Grignard reagents.

[0043] The inventive compounds can be used in plastic materials orplastic objects of any type and shape for a plurality of purposes, forwhich the photochromic behavior is of importance. Moreover, a dye of thepresent invention or a mixture of such dyes can be used. For example,the photochromic naphthopyran dyes of the present invention can be usedin lenses, particularly in ophthalmic lenses, lenses for eyeglass of alltypes, such as ski goggles, sunglasses, motorcycles goggles, visors ofhelmets and the like. Moreover, the inventive naphthopyrans can also beused, for example, as sun protection in vehicles and residences in theform of windows, protective shutters, coverings, roofs or the like.

[0044] To prepare such photochromic objects, the inventive photochromicnaphthopyran dyes can be applied by various methods, described in thestate of the art, such as those already given in WO 99/15518, on apolymer material, such as an organic synthetic resin material, orembedded therein.

[0045] In this connection, a differentiation is made between bulk dyeingmethods and surface dyeing methods. A bulk dye method comprises, forexample, the dissolving or dispersing of the inventive photochromiccompound or compounds in a synthetic resin material, for example, by theaddition of the photochromic compound or compounds to a monomericmaterial, before polymerization takes place. A further possibility ofproducing a photochromic object is the penetration of the syntheticresin material or materials with the photochromic compound or compoundsby immersing the synthetic resin material in a hot solution of thephotochromic dye or dyes of the present invention or, for example, by aheat transfer method. The photochromic compound or compounds can also beprovided, for example, in the form of a separate layer between adjoininglayers of the synthetic resin material, such as a part of a polymericfilm. Moreover, the photochromic compound or compounds can also beapplied as part of a coating present on the surface of the syntheticresin material. The expression “penetration” is intended to signify themigration of the photochromic compound or compounds into the syntheticresin material, for example, by the solvent-supported transfer of thephotochromic compound or compounds into a polymer matrix, by the vaporface transfer or by different types of surface diffusion processes.Advantageously, such photochromic objects, such as eyeglass lenses, canbe produced not only by means of the conventional bulk dyeing, but also,in a similar manner, by means of surface dyeing. For the lattervariation, a surprising slight tendency to migrate can be achieved. Thisis of advantage especially for the subsequent finishing steps, sincelayer detachments and similar defects are drastically reduced, forexample, during an anti-reflection coating, due to the lesser backdiffusion under vacuum.

[0046] Overall, on the basis of the inventive photochromic2H-naphtho[1,2-b]pyrans, any dyes, which are compatible from a chemicaland color point of view, can be applied on or embedded in the syntheticresin material in order to satisfy esthetic points of view as well asmedical or fashion points of view. The dye or dyes, specificallyselected, can therefore be varied depending on the intended effect aswell as on the requirements.

[0047] In the following, the synthesis of inventive2H-naphtho[1,2-b]pyrans, selected by way of example, is explained indetail, these examples serving, of course, only as illustration and donot limit the scope of the present invention.

EXAMPLES Example 1 Synthesis ofspiro-9′-xanthene-5-[2-(4-methoxyphenyl)-2-phenyl-5,6,7,8-tetrahydro-6,6,7,7-tetramethyl-phenanthro[9,10-b]pyran]

[0048] i) Aluminum chloride (24.5 g) and 14.5 g of tetramethylsuccinylanhydride (A. v. Auwers, N. Ungemach, Chem. Ber. 1935, 68, 349) weretreated with stirring and cooling with ice water with 14.7 g ofmethoxynaphthalene. The mixture, after being thawed and stirredovernight, was poured onto ice water. The resulting precipitate wassubsequently filtered off. The acid was purified over its sodium saltand recrystallized from acetic acid. The colorless solid (18 g) wasidentified by means of NMR spectroscopy to beβ-(4-methoxy-1-naphthoyl)-α-α-β-β-tetramethylpropionic acid.

[0049] ii) The keto acid so obtained (10 g) was heated for 8 hours at130° to 135° C. with 10 g of potassium hydroxide and 8 g of 80%hydrazine hydrate in 50 mL of diethylene glycol. After the water and theexcess hydrazine hydrate were distilled off, the temperature wasmaintained at 210° C. for 3 hours and subsequently lowered to 90° C., atwhich temperature the product was poured onto a mixture of 200 g of iceand 50 mL of concentrated hydrochloric acid. The resulting precipitatewas filtered off with suction and washed until neutral. The solidsubsequently was stirred with 14 mL of dimethylsulfate in 80 mL of 10%sodium hydroxide solution at 40° to 50° C. The ester, formed as anintermediate, was subsequently saponified under reflux. The solution wascooled and acidified and the resulting precipitate was filtered off withsuction and washed until neutral. The product (7.5 g) was identified bymeans of NMR spectroscopy asγ-(4-methoxy-1-naphthyl)-α,α,β,β-tetramethylbutyric acid.

[0050] iii) A suspension of 5 g of the acid, obtained in step ii), wastreated in 100 mL of anhydrous ether and 2 drops of pyridine with 4 mLof thionyl chloride and refluxed for 1 hour. After cooling, the solventwas distilled off under vacuum and the residue dissolved in 50 mL and,while being stirred and cooled with ice water, treated with 8 mL of tintetrachloride. The mixture was stirred for 15 minutes and subsequentlypoured onto a mixture of 100 mL of ice water and 25 mL of concentratedhydrochloric acid. The organic phase was separated off and washed onceeach with dilute hydrochloric acid, water and ammonium hydroxidesolution. After the solvent was distilled off under vacuum, a lightyellow residue (4.1 g) remained behind, which was identified by means ofNMR spectroscopy as being1,2,3,4-tetrahydro-9-methoxy-2,2,3,3-tetramethyl-1-oxo-phenanthrene.

[0051] iv) The reaction product (4 g), obtained in step iii) wasrefluxed in a mixture of 20 mL of 48% hydrogen bromide and 20 mL ofglacial acetic acid for 3 hours. After cooling, the formulation waspoured into water, made alkaline and washed twice with ether. Thesolution was acidified and the resulting precipitate filtered off withsuction and washed until neutral. The product (3.5 g) was identified bymeans of NMR spectroscopy as being1,2,3,4-tetrahydro-9-hydroxy-2,2,3,3-tetramethyl-1-oxo-phenanthrene.

[0052] v) The phenanthrene derivative (3 g), obtained in step iv), wassuspended with 4.6 g of 1-(4-methoxyphenyl)-1-phenyl-1-propinol(produced from 4-methoxybenzo-phenone and sodium acetylide in DMSO) in100 mL of toluene. After addition of a spatula tip of 4-toluenesulfonicacid, the mixture was refluxed for 2 hours, a solution being formed.After cooling, half the solvent was distilled off under vacuum and theremaining solution chromatographed on aluminum oxide, having a watercontent of 3%, with a 1:1 mixture of dichloromethane and methane. Forthe final purification, the crude product was digested in 50 mL ofmethanol. The solid was filtered off with suction, washed with methanoland dried. The light yellow powder (4.1 g) was identified by means ofNMR spectroscopy as being2-(4-methoxyphenyl)-2-phenyl-5,6,7,8-tetrahydro-6,6,7,7-tetramethyl-5-oxo-phenanthro-[9,10-b]pyran(4 g).

[0053] vi) The reaction product (2 g), obtained in step v), wasdissolved with stirring in 50 mL of anhydrous THF and treated with twoequivalents of 2-phenoxyphenyl magnesium bromide (synthesized from2-bromodiphenylether and magnesium shavings in THF solution). Themixture was stirred for 10 hours at room temperature and hydrolyzed withaqueous ammonium chloride solution. After addition of 100 mL ofdichloromethane, the organic phase was separated off, washed with waterand dried over sodium sulfate. After the solvent was distilled off, theresidue was digested with methanol. By means of NMR spectroscopy, theresidue was identified as being5-hydroxy-2-(4-methoxyphenyl)-5-(2-phenoxyphenyl)-2-phenyl-5,6,7,8-tetrahydro-6,6,7,7-tetramethylphenanthro[9,10-b]pyran(1.1 g), which was used further as crude product.

[0054] vii) The reaction product (0.8 g), obtained in step vi), wascyclized in 30 mL of hot glacial acetic acid by the method of R. G.Clarkson, M. Gomberg, J. Am. Chem. Soc. 1930, page 2881. After theaddition of a drop of hydrochloric acid, the temperature was raised tothe boiling point for 5 minutes, after which water was added until thereaction solution became cloudy. After cooling, the precipitate wasfiltered off with suction, washed until neutral and dried carefully. Forthe final purification, the solid was dissolved in 30 mL ofdichloromethane and chromatographed on aluminum oxide, having a watercontent of 3%, with a 1:1 mixture of dichloromethane and hexane. Afterdigestion with hexane, a beige colored powder (0.3 g) was obtained,which was identified by NMR spectroscopy as beingspiro-9′-xanthene-5-[2-(4-methoxyphenyl)-2-phenyl-5,6,7,8-tetrahydro-6,6,7,7-tetramethylphenanthro[9,10-b]pyran].

Example 2 Synthesis ofspiro-9′-fluorene-5-{2-[4-(N-morpholinyl)phenyl]-2-phenyl-5,6,7,8-tetrahydrophenanthro[9,10-b]pyran}

[0055] Starting from methoxynaphthalene and succinic anhydride,1,2,3,4-tetrahydro-9-methoxy-1-oxophenanthrene was synthesized first bya method similar to steps i) to iii) of Example 1 (see W. E. Bachmannand D. W. Holmes, (J. Chem. Soc. 1940, 62, page 2750). The demethylation(step iv) was carried out by the method of G. A. R. Kon and F. C. J.Ruzicka (J. Chem. Soc. 1936, page 187).

[0056] Subsequently, the reaction was carried out as in Example 1, withthe exception that, in step v), the reaction was carried out with1-[4-(N-morpholinyl)phenyl]-1-phenyl-1-propinol (synthesized from4-(N-morpholinyl)benzophenone) (H. Kotsuki, Synthesis 1990, page 1145)and sodium acetylide in DMSO) instead of with1-(4-methoxyphenyl)-1-phenyl-1-propinol.2-[4-(N-Morpholinyl)phenyl]-2-phenyl-5,6,7,8-tetrahydro-5-oxo-phenanthro[9,10-b]pyranwas obtained which, as in Example 1, was reacted in the subsequent stepvi) with 2-biphenylyl magnesium bromide (synthesized from2-bromobiphenyl and magnesium shavings in THF solution) to form5-hydroxy-5-(2-biphenylyl)-2-[4-(N-morpholinyl)phenyl]-2-phenyl-5,6,7,8-tetrahydrophenanthro[9,10-b]pyran].As in Example 1, the cyclization tospiro-9′-fluorene-5-{2-[4-(N-morpholinyl)phenyl]-2-phenyl-5,6,7,8-tetrahydrophenanthro[9,10-b]pyran}(0.3 g) was carried out in the subsequent step vii), as confirmed by NMRspectroscopy.

Example 3 Synthesis of5-hydroxy-2,2,5-triphenyl-5,6,7,8-tetrahydro-phenanthro[9,10-b]pyran

[0057] The method was similar to that of Example 2 with the exceptionthat, in step v), the reaction was carried out with1,1-diphenyl-1-propinol [synthesized from benzophenone and sodiumacetylide in DMSO], instead of with1-[4-(N-morpholinyl)phenyl]-1-phenyl-1-propinol.2,2-Diphenyl-5,6,7,8-tetrahydro-5-oxo-phenanthro[9,10-b]pyran wasobtained, which was reacted, as in step vi) of Example 1, with twoequivalents of a 2 molar solution of phenyl magnesium chloride in THF.The crude product thus obtained was chromatographed with dichloromethaneon aluminum oxide, having a water content of 3%. The beige coloredproduct (0.5 g) was identified by means of NMR spectroscopy as being5-hydroxy-2,2,5-triphenyl-5,6,7,8-tetrahydrophenanthro[9,10-b]pyran.

Example 4 Synthesis ofspiro-9′-{(9,10-dihydroanthracene)-5-[2,2-bis(4-methoxy-phenyl)]-cyclopenta[f]naphtho[1,2-b]pyran}

[0058] Instead of1,2,3,4-tetrahydro-9-hydroxy-2,2,3,3-tetramethyl-1-oxo-phenanthrene,4,5-benzo-8-hydroxy-indan-1-one (see T. Sasaki, K. Kanematsu, K.Hayakawa, A. Kondo, J. Org. Chem. 1973, 38, page 4100) was used in stepv) of Example 1. The latter was reacted with1,1,-bis(4-methoxyphenyl)-1-propinol (synthesized from4,4′-dimethoxybenzophenone and sodium acetylide in DMSO).2,2-Bis(4-methoxyphenyl)-5-oxo-cyclopenta[c]naphthopyran was obtainedwhich, as in Example 1, was reacted in the subsequent step vi) with2-benzylphenyl magnesium bromide (synthesized from2-bromodiphenylmethane and magnesium in THF solution) to5-(2-benzylphenyl)-5-hydroxy-2,2-bis(4-methoxyphenyl)-cyclopenta[f]naphthopyran.As in Example 1, the cyclization to spiro-9′- {(9,10-dihydroanthracene)-5-[2,2-bis(4-methoxyphenyl)]-cyclopenta[c]naphtha[1,2-b]pyran}(0.4 g) was carried out in the subsequent step (vii), as confirmed bymeans of NMR spectroscopy.

1. Photochromic 2H-naphtho-[1,2-b]pyrans of the general formula (I) aremade available

wherein X represents a ring element with 2 to 4 saturated and/orunsaturated carbon atoms, of which not more than one can be replaced bya hetero atom, selected from the group comprising O, S and NR₄, R₄ beinga linear or branched C₁ to C₆ alkyl group, a substituted orunsubstituted C₅ to C₇ cycloalkyl group, a substituted or unsubstitutedphenyl group or a substituted or unsubstituted benzyl group; R₁ is asubstituent, selected from group A, comprising a C₁ to C₆ alkyl group, aC₁ to C₆ alkoxy group, a C₃ to C₇ cycloalkyl group, which may have oneor more hetero atoms, a phenyl group, a hydroxy group, bromine, chlorineand fluorine, n being 0, 1 or 2; R₂, R₃ independently of one another aregroups, selected from group G, comprising hydrogen, hydroxy, a C₁ to C₆alkyl group, a C₁ to C₆ alkoxy group, a C₃ to C₇ cycloalkyl group, anunsubstituted, monosubstituted and disubstituted phenyl group and anunsubstituted, monosubstituted and disubstituted naphthyl group and thearomatic groups, selected from group C, comprising benzene, naphthalene,phenanthrene, pyridine, quinoline, furan, thiophene, pyrrol, benzofuran,benzothiophene, indol and carbazol, the substituent or substituents ofthe aforementioned aromatic groups being selected from group A; or R₂and R₃ together, with inclusion of the spiro carbon atom, form a5-membered to 11-membered ring, to which one or several aromatic orheteroaromatic ring systems may be annellated, the aromatic orheteroaromatic ring system or systems being one of the aforementionedgroup C; or R₂ and R₃ together represent an oxygen atom with formationof a carbonyl group; with the proviso that, when X is —(CH₂)₂—0 or—(CH₂)₃— and R₂ and R₃ are not at the same time hydrogen; B, B′ areselected independently of one another from the following groups a), b)or c), wherein a) are mono-, di- and trisubstituted aryl groups, thearyl group being phenyl or naphthyl; b) are unsubstituted, mono- anddisubstituted heteroaryl groups, the heteroaryl group being pyridyl,furanyl, benzofuran-2-yl, benzofuran-3-yl, thienyl, benzothien-2-yl orbenzothien-3-yl; the substituents of the aryl groups or the heteroarylgroups in a) and b) being selected from a group comprising hydroxy,amino, mono-(C₁ to C₆)-alkylamino, di-(C₁ to C₆)-alkylamino, mono- anddiphenylamino, unsubstituted, monosubstituted or disubstituted at thearomatic ring, piperidinyl, morpholinyl, carbazolyl, unsubstituted,monosubstituted and disubstituted pyrryl, C, to C₆ alkyl, C₁ to C₆alkoxy, bromine, chlorine and fluorine, wherein the aforementionedaromatic and heteroaromatic ring systems can be substituted with C₁ toC₆ alkyl, C₁ to C₆ alkoxy, bromine, chlorine and fluorine; c) arestructure units with the following formulas (V) and (W)

wherein Y and Z, independently of one another are O, S, CH, CH₂ or NR₈,the R₈ group is selected from the group D comprising C₁ to C₆ alkyl, C₁to C₆ acyl and hydrogen, and R₅ in each case is a substituent from groupA, n being defined as above; and R₆ and R₇, independently of oneanother, are hydrogen and/or a C₁ to C₆ alkyl group, with the provisothat, when Y in formula (V) is NR₈, Z is a carbon atom; or d) B and B′form with one another an unsubstituted, monosubstituted or disubstitutedfluorene-9-ylidene group or a saturated hydrocarbon group, which is C₃to C₁₂, spiro-monocyclic, C₇ to C₁₂ spiro-bicyclic and/or C₇-C₁₂spiro-tricyclic, the fluoreno substituents being selected from Group A.2. The photochromic 2H-naphtho[1,2-b]pyrans of claim 1, the carbon atomsin the ring element X being saturated.
 3. The photochromic2H-naphtho[1,2-b]pyrans of claims 1 or 2, the carbon atoms in the ringelement X being monosubstituted or disubstituted, the substituent orsubstituents being selected from group A, comprising C₁ to C₆ alkyl, C₁to C₆ alkoxy, phenyl, bromine, chlorine and fluorine.
 4. Thephotochromic 2H-naphtho[1,2-b]pyrans of one of the preceding claims,which have the general formula (II)

wherein n, R₁, R₂, R₃ and X are defined as above with the proviso thatthe R₁ groups and n in each case can be the same or different.
 5. Thephotochromic 2H-naphtho[1,2-b]pyrans of one of the preceding claims,which have the general formula (III)

wherein n, R₁, X, B and B′ are defined as above.
 6. The photochromic2H-naphtho[1,2-b]pyrans of one of the preceding claims, which arespiro-9′-xanthene-5-[2-(4-methoxyphenyl)-2-phenyl-5,6,7,8-tetrahydro-6,6,7,7-tetramethyl-phenanthro[9,10-b]pyran]spiro-9′-fluorene-5-{2-[4-(N-morpholinyl)phenyl]-2-phenyl-5,6,7,8-tetrahydrophenanthro[9,10-b]pyran}5-hydroxy-2,2,5-triphenyl-5,6,7,8-tetrahydro-phenanthro[9,10-b]pyranspiro-9′-{(9,10-dihydroanthracene)5-[2,2-bis(4-methoxyphenyl)]-cyclopenta[f]naphtho[1,2-b]pyran}2-[4-(N-morpholinyl)phenyl]-2-phenyl-5-oxo-cyclopenta[f]naphthopyran2-[4-(N-morpholinyl)phenyl]-2-phenyl-5,6,7,8-tetrahydro-5-oxo-phenanthro[9,10-b]pyran]spiro-9′-fluorene-5-[2-(4-methoxyphenyl)-2-phenyl-cyclopenta-[f]naphtho[1,2-b]pyran]spiro-9′-xanthene-5-{-2-[4-(N-morpholinyl)phenyl]-2-phenyl-5,6,7,8-tetrahydro-6,6,7,7,-tetramethyl-phenanthro[9,10-b]pyran}spiro-9′-fluorene-5-[2-(4-methoxyphenyl)-2-phenyl-cyclohepta[f]naphtho[1,2-b]pyran]andspiro-9′-fluorene-5-[2-(4-methoxyphenyl)-2-phenyl-oxepano[3,2-f]naphtho[1,2-b]pyran].7. The use of the photochromic 2H-naphtho[1,2-b]pyrans of one of theclaims 1 to 6 in synthetic resin materials.
 8. The use of claim 7,wherein the synthetic resin material is an ophthalmic lens.